Preparation method of tobacco sheets with a reduced quantity of wood pulp fibers

ABSTRACT

The present invention provides a preparation method of tobacco sheets with a reduced quantity of wood pulp fibers, and belongs to the technical field of reconstituted tobacco. The method includes the steps of: cooking tobacco stem materials by alkaline process, and filtering and washing the cooked tobacco stem materials to obtain tobacco stem fibers; generating mixed pulp by mixing wood pulp fibers, tobacco pulp, filling materials, water and the tobacco stem fibers together as per certain proportions, and subjecting the mixed pulp to a papermaking process in a paper machine to obtain tobacco sheets. By means of adding tobacco stem fibers, the present invention effectively reduces the quantity of wood pulp fibers, ensures the continuous operation of the paper machine, and effectively improves the bulk and tensile index of prepared tobacco sheets. Furthermore, the present invention reduces the quantity of wood pulp fibers, improves the flavor of tobacco, and effectively relieves the negative effect of excessive wood pulp fibers on the flavor of tobacco.

TECHNICAL FIELD

The present invention relates to the field of reconstituted tobacco, inparticular to a preparation method of tobacco sheets with a reducedquantity of wood pulp fibers.

BACKGROUND

The production of tobacco sheets is most commonly done by thepapermaking process. In order to keep the paper machine in continuousoperation during production, some wood pulp fibers for making papergenerally need to be added in the process of producing tobacco sheets.This addition enables tobacco pulp to be molded smoothly in thepapermaking system, ensuring continuous operation of the paper machine.Furthermore, the added wood pulp fibers can serve as the skeleton oftobacco sheets to help improve the strength of tobacco sheets.

However, adding wood pulp fibers has certain negative effects on theflavor of tobacco sheets. The addition of wood pulp fibers produces awood smell in smoking tobacco sheets, thus reducing the original scentof tobacco.

SUMMARY

In order to solve the aforementioned technical problem, the preventinvention provides a preparation method of tobacco sheets with a reducedquantity of wood pulp fibers. The preparation method disclosed by thepresent invention effectively reduces the quantity of wood pulp fibersand still allows tobacco pulp to be molded smoothly in the papermakingsystem. In addition, the resulting tobacco sheets have high or increasedstrength.

The present invention provides a preparation method of tobacco sheetswith a reduced quantity of wood pulp fibers, including the followingsteps:

(1) cooking tobacco stem materials by alkaline process, and filteringand washing the cooked tobacco stem materials to obtain tobacco stemfibers; and

(2) generating mixed pulp by mixing wood pulp fibers, tobacco pulp,filling materials, water and the tobacco stem fibers obtained in step(1) together as per certain proportions, and subjecting the mixed pulpto a papermaking process in a paper machine to obtain tobacco sheets.

Preferably, the length of the tobacco stem fibers in step (1) ispreferably about 0.1-0.5 mm and the diameter is about 0.5-2 p.m.

Preferably, in step (1), strong alkali, the tobacco stem materials andwater are mixed and then cooked, the mass concentration of the strongalkali is 15-50%, and the mass ratio of the tobacco stem materials tothe strong alkali is (4.5-5.5):1.

Preferably, in step (1), the temperature for cooking is 150-180° C. andthe time for cooking is 1-4 h.

Preferably, in step (2), the mass content of the tobacco stem fibers inthe mixed pulp is 0.1-3%.

Preferably, in step (2), the mass content of the wood pulp fibers in themixed pulp is 14-22%.

Preferably, in step (2), the filling materials comprise calciumcarbonate.

Preferably, in step (2), the mass content of the filling materials inthe mixed pulp is 8-20%.

Preferably, in step (2), the tobacco pulp includes tobacco stem pulp andtobacco leaf pulp, and the mass concentration of the tobacco pulp is5-15%.

Preferably, in step (2), the mass concentration of the mixed pulp in thetobacco sheets is 0.1-1.0%.

The preparation method of the tobacco sheets with a reduced quantity ofwood pulp fibers, provided by the invention includes the steps of:cooking tobacco stem materials by alkaline process, and filtering andwashing the cooked tobacco stem materials to obtain tobacco stem fibers;generating mixed pulp by mixing wood pulp fibers, tobacco pulp, fillingmaterials, water and the tobacco stem fibers together as per certainproportions, and subjecting the mixed pulp to a papermaking process in apaper machine to obtain tobacco sheets. By means of adding tobacco stemfibers, the present invention effectively reduces the quantity of woodpulp fibers, ensures the continuous operation of the paper machine, andeffectively improves the bulk and tensile index of prepared tobaccosheets. Furthermore, by reducing the quantity of wood pulp fibers, thepresent invention improves the flavor of tobacco effectively relievingthe negative effect of excessive wood pulp fibers on the flavor oftobacco.

BRIEF DESCRIPTION OF THE DRAWING

FIG. 1 shows a scanning electron microscope picture of the tobacco stemfibers after being cooked in a strong alkali solution in preferredembodiment 1 of the present invention.

DETAILED DESCRIPTION

The present invention provides a preparation method of tobacco sheetswith a reduced quantity of wood pulp fibers, which includes thefollowing steps:

(1) cooking tobacco stem materials by alkaline process, and filteringand washing the cooked tobacco stem materials to obtain tobacco stemfibers; and

(2) generating mixed pulp by mixing wood pulp fibers, tobacco pulp,filling materials, water and the tobacco stem fibers obtained in step(1) together as per certain proportions, and subjecting the mixed pulpto a papermaking process in a paper machine to obtain tobacco sheets.

In the present invention, an alkaline process is adopted to cook tobaccostem materials to obtain cooked aqueous pulp.

In the present invention, an aqueous solution of strong alkali, thetobacco stem materials and water are mixed and then cooked. The massconcentration of the aqueous solution of strong alkali is preferably15-50%, more preferably 20-40%, and most preferably 25-35%. The aqueoussolution of strong alkali preferably includes an aqueous sodium orpotassium hydroxide solution.

In the present invention, the mass ratio of the tobacco stem materialsto the aqueous solution of strong alkali is preferably (4.5-5.5):1 andmore preferably 5:1.

In the present invention, the solid-liquid mass ratio in the mixture ofthe aqueous solution of strong alkali, tobacco stem materials and wateris preferably 1:(4.5-5.5) and more preferably 1:5.

In the present invention, the temperature for the cooking is preferably150-180° C. and more preferably 160-170° C.; the time is preferably 1-4h and more preferably 2-3 h.

In cooking by alkaline process in the present invention, substances intobacco stems such as lignin and pectin can dissolve in the strongalkali solution. Tobacco stem fibers in tobacco stems are insoluble inthe strong alkali solution. Follow-up filtration helps extract tobaccostem fibers.

Cooked aqueous pulp is obtained after cooking. In the present invention,the cooked aqueous pulp is filtered to obtain tobacco stem fibers.

The present invention imposes no specific limitation on theimplementation of filtration in the present invention, and any mode offiltration well known by those skilled in the art may be adopted.

After filtration, the cooked fibers are preferably washed with water.The present invention imposes no specific limitation on theimplementation of washing in the present invention, and any washing modewell known by those skilled in the art may be adopted.

In the present invention, the length of the tobacco stem fibers obtainedby the above modes is preferably 0.1-0.5 mm and more preferably 0.2-0.4mm; the diameter is preferably 0.5-2 μm and more preferably 1.0-1.5 μm;the Kappa number of the tobacco stem fibers is preferably 3-10, morepreferably 4-9 and most preferably 5-8. In the present invention, thetobacco stem fibers, having been cooked in the strong alkaline solution,have ideal length, diameter and Kappa number, and thus, the strength oftobacco sheets is improved and the smooth operation of the paper machineis ensured.

In the present invention, after the tobacco stem fibers are obtained,mixed pulp is generated by mixing wood pulp fibers, tobacco pulp,filling materials, water and the tobacco stem fibers together as percertain proportions, and tobacco sheets are obtained by subjecting themixed pulp to a papermaking process in a paper machine.

In the present invention, the mass content of the wood pulp fibers inthe mixed pulp is preferably 14-22%, more preferably 15-19% and mostpreferably 16-18%.

In the present invention, the mass content of the tobacco stem fibers inthe mixed pulp is preferably 0.1-3%, more preferably 0.5-2.5% and mostpreferably 1.0-2.0%.

By adding tobacco stem fibers during the preparation of tobacco sheets,the present invention effectively reduces the quantity of wood pulpfibers and effectively improves the strength of tobacco sheets.

In the present invention, the tobacco pulp preferably includes tobaccostem pulp and tobacco leaf pulp; the mass concentration of the tobaccopulp is preferably 5-15% and more preferably 8-12%. In the presentinvention, the solvent in the tobacco pulp is preferably water.

In the present invention, the filling materials preferably includecalcium carbonate. The mass content of the filling materials in themixed pulp is preferably 8-20%, more preferably 10-15% and mostpreferably 12-14%.

In the present invention, the mass concentration of the mixed pulp ispreferably 0.1-1.0% and more preferably 0.5%.

The obtained mixed pulp is subjected to a papermaking process in thepaper machine in the present invention to obtain tobacco sheets.

In the present invention, the retention agent added during the papermaking process in the paper machine preferably includes cationic guargum or chitosan. The mass ratio of the retention agent to the mixed pulpis preferably (0.05-0.3%):1, more preferably (0.1-0.25%):1 and mostpreferably (0.15-0.2%):1.

The present invention imposes no specific limitation on theimplementation of the papermaking process in the paper machine in thepresent invention, and any papermaking mode in the paper machine wellknown by those skilled in the art may be adopted.

The technical scheme in the present invention will now be describedclearly and fully detailed with reference to the following preferredembodiments in the present invention.

Preferred Embodiment 1

10 kg of tobacco stem materials and 2 kg of aqueous sodium hydroxidesolution (50% mass concentration) are added with water to make thesolid-liquid mass ratio in the reaction system be 1:5, wherein thecooking conditions are 170° C. for 3 h. After cooking, the cookedaqueous pulp is filtered and the filter cakes are washed with water toobtain tobacco stem fibers.

The mixed pulp is prepared as per certain mass proportions: 100 parts oftobacco pulp (10% mass concentration), 20 parts of wood pulp fibers, 0.5parts of tobacco stem fibers, and 15 parts calcium carbonate; and a 0.5%mass concentration of the mixed pulp is obtained by adding water.Tobacco sheets are obtained by papermaking process in the paper machine.Cationic guar gum is added as a retention agent during the papermakingprocess.

FIG. 1 shows a scanning electron microscope picture of the tobacco stemfibers after being cooked in an aqueous sodium hydroxide solution.

Preferred Embodiment 2

Testing is conducted according to the method in preferred embodiment 1,except that there are 1.0 parts of tobacco stem fibers utilized in themixed pulp preparation, not 0.5 parts as specified in preferredembodiment 1.

Preferred Embodiment 3

Testing is conducted according to the method in preferred embodiment 1,except that there are 2.0 parts of tobacco stem fibers utilized in themixed pulp preparation, not 0.5 parts as specified in preferredembodiment 1.

Preferred Embodiment 4

Testing is conducted according to the method in preferred embodiment 1,except that there are 4.0 parts of tobacco stem fibers utilized in themixed pulp preparation, not 0.5 parts as specified in preferredembodiment 1.

REFERENCE EXAMPLE 1

Testing is conducted according to the method in preferred embodiment 1,except that 0 parts of tobacco stem fibers and 25 parts of wood pulpfibers are utilized in the mixed pulp preparation, not 0.5 parts and 20parts, as specified in preferred embodiment 1, respectively.

REFERENCE EXAMPLE 2

Testing is conducted according to the method in preferred embodiment 1,except that 0 parts of tobacco stem fibers are utilized in the mixedpulp preparation, not 0.5 parts as specified in preferred embodiment 1,respectively.

The strength of the tobacco sheets prepared respectively by embodiments1-4 and reference examples 1-2 is tested, with the test results shown inTable 1:

TABLE 1 Effects of quantity of tobacco stem fibers on physicalproperties of tobacco sheets Reference Reference Embodiment EmbodimentEmbodiment Embodiment example 1 example 2 1 2 3 4 Wood pulp fibers 25parts 20 parts Tobacco stem fibers 0 0 0.5 part 1.0 part 2.0 parts 4.0parts Bulk (cm³/g) 2.04 2.06 2.10 2.11 2.07 2.03 Tensile index (N · m/g)11.18 10.20 10.32 11.77 12.80 13.89

As can be seen from the test results in Table 1, the present inventioneffectively reduces the quantity of wood pulp fibers and improves thebulk and tensile index (after 1.0 part) of the tobacco sheets by addingtobacco stem fibers.

Preferred Embodiment 5

Testing is conducted according to the method in preferred embodiment 1,except that 16 parts of wood pulp fibers, and 0.5 parts, 1.0 parts, and2.0 parts of the tobacco stem fibers are utilized in the mixed pulppreparation, respectively. The physical properties of the tobacco sheetsobtained by adding different amounts of tobacco stem fibers are testedrespectively, with the test results shown in Table 2.

REFERENCE EXAMPLE 3

Testing is conducted according to the method in preferred embodiment 5,with the distinction that no tobacco stem fibers are added. The physicalproperties of the resulting tobacco sheets are tested, with the testresults shown in Table 2.

TABLE 2 Effects of the quantity of tobacco stem fibers on physicalproperties of tobacco sheets Reference example 3 Embodiment 5 Quantityof wood pulp 16 parts fibers Quantity of tobacco stem 0 0.5 part 1.0part 2.0 parts 4.0 parts fibers Bulk (cm³/g) 2.09 2.07 2.13 2.17 2.16Tensile index (N · m/g) 9.09 9.31 11.12 11.43 12.69

As can be seen from Table 2, the present invention effectively improvesthe bulk (after 1.0 part) and tensile index of the prepared tobaccosheets by adding tobacco stem fibers.

Preferred Embodiment 6

Testing is conducted according to the method in preferred embodiment 1,except that 12 parts of wood pulp fibers and 2.0 parts, 4.0 parts, 6.0parts, and 8.0 parts of tobacco stem fibers are utilized, respectively,in the mixed pulp preparation. The physical properties of the tobaccosheets obtained by adding different amounts of tobacco stem fibers aretested respectively, with the test results shown in Table 3.

REFERENCE EXAMPLE 4

Testing is conducted according to the method in preferred embodiment 6,with the distinction that no tobacco stem fibers are added. The physicalproperties of the resulting tobacco sheets are tested, with the testresults shown in Table 3.

TABLE 3 Effects of the quantity of tobacco stem fibers on physicalproperties of tobacco sheets Reference example 4 Embodiment 6 Quantityof wood pulp 12 parts fibers Quantity of tobacco stem 0 2.0 parts 4.0parts 6.0 parts 8.0 parts fibers Bulk (cm³/g) 2.14 2.10 2.18 2.17 2.16Tensile index (N · m/g) 8.37 9.88 10.69 11.78 12.95

As can be seen from Table 3, the present invention effectively improvesthe bulk (after 4.0 part) and tensile index of the finally-preparedtobacco sheets by adding tobacco stem fibers.

As evidenced by the above mentioned preferred embodiments, by addingtobacco stem fibers the present invention effectively reduces thequantity of wood pulp fibers, ensuring the continuous operation of thepaper machine and effectively improving the bulk and tensile index ofprepared tobacco sheets. Furthermore, by reducing the quantity of woodpulp fibers, the present invention improves the flavor of tobacco,effectively relieving the negative effect of excessive wood pulp fiberson the flavor of tobacco.

The foregoing descriptions are only preferred embodiments of the presentinvention. It should be noted that for one ordinary skilled in the art,several improvements and modifications may further be made withoutdeparting from the principle of the present invention. Theseimprovements and modifications should also be deemed as falling withinthe protection scope of the present invention.

What is claimed is:
 1. A preparation method of tobacco sheets with areduced quantity of wood pulp fibers, comprising the following steps:(1) cooking tobacco stem materials by alkaline process, and filteringand washing the cooked tobacco stem materials to obtain tobacco stemfibers; and (2) generating mixed pulp by mixing wood pulp fibers,tobacco pulp, filling materials, water and the tobacco stem fibersobtained in step (1) together as per certain proportions, and subjectingthe mixed pulp to a papermaking process in a paper machine to obtaintobacco sheets.
 2. The preparation method according to claim 1, whereinthe tobacco stem fibers in step (1) have a length of 0.1-0.5 mm and adiameter of 0.5-2 μm.
 3. The preparation method according to claim 1,wherein in step (1), strong alkali, the tobacco stem materials and waterare mixed and then cooked, the strong alkali has a mass concentration of15-50%, and a mass ratio of the tobacco stem materials to the strongalkali is (4.5-5.5):1.
 4. The preparation method according to claim 2,wherein in step (1), strong alkali, the tobacco stem materials and waterare mixed and then cooked, the strong alkali has a mass concentration of15-50%, a mass ratio of the tobacco stem materials to the strong alkaliis (4.5-5.5):1.
 5. The preparation method according to claim 1, whereinin step (1), the cooking is conducted at a temperature of 150-180° C.for a time of 1-4 h.
 6. The preparation method according to claim 2,wherein in step (1), the cooking is conducted at a temperature of150-180° C. and a time of cooking is 1-4 h.
 7. The preparation methodaccording to claim 1, wherein in step (2), the tobacco stem fibers inthe mixed pulp have a mass content of 0.1-3%.
 8. The preparation methodaccording to claim 1, wherein in step (2), the wood pulp fibers in themixed pulp have a mass content of 14-22%.
 9. The preparation methodaccording to claim 7, wherein in step (2), the wood pulp fibers in themixed pulp have a mass content of 14-22%.
 10. The preparation methodaccording to claim 1, wherein in step (2), the filling materialscomprise calcium carbonate.
 11. The preparation method according toclaim 1, wherein in step (2), the filling materials in the mixed pulphave a mass content of 8-20%.
 12. The preparation method according toclaim 1, wherein in step (2), the filling materials comprise calciumcarbonate and wherein the filling materials in the mixed pulp have amass content of 8-20%.
 13. The preparation method according to claim 1,wherein in step (2), the tobacco pulp comprises tobacco stem pulp andtobacco leaf pulp, and the tobacco pulp has a mass concentration of5-15%.
 14. The preparation method according to claim 1, wherein in step(2), the mixed pulp has a mass concentration of 0.1-1.0%.
 15. Thepreparation method according to claim 7, wherein in step (2), the mixedpulp has a mass concentration of 0.1-1.0%.
 16. The preparation methodaccording to claim 10, wherein in step (2), the mixed pulp has a massconcentration of 0.1-1.0%.
 17. The preparation method according to claim13, wherein in step (2), the mixed pulp has a mass concentration of0.1-1.0%.